Domestic hot water storage supply system



y 1957 R. E. WARNER 3,330,332

DOMESTIC HOT WATER STORAGE SUPPLY SYSTEM Filed Jan. 27, 1965 2 Sheets-Sheet 1 F I G A2 INVENTOR.

ROBERT E T/I/AFPNER ATTORNEYS July 11, 1967 R. E. WARNER DOMESTIC HOT WATER STORAGE SUPPLY SYSTEM 2 Sheets-Sheet 2 Filed Jan. 27-, 1965 M I 5 7 u I P 2, "#3 3 I I I 2 I I 0 07 I is M flux/Z 9 w I 2 Q1 1 I 6 I I 1. w I 0 I I 5 1 3 I% T I I a 6/0 D I 9 9 Ha I nfl lu I a I I n L 4 0 Q/ a w I I F r I I 6 4/ 2, 0/ 0 0 0 INVENTOR MPNEF? zymw ATTORNEYS United States Patent ()fiFice 3,33%,332 Patented July 11, 1967 3,330,332 DOMESTIC HOT WATER STORAGE SUPPLY SYSTEM Robert E. Warner, 4616 Lynwood Terrace, Minnetonka, Minn. 55345 Filed Jan. 27, 1965, Ser. No. 428,292 3 Claims. (Cl. 165-26) The present invention pertains to a new and improved domestic hot water storage supply system and in particular to a hot water storage supply system in which the water passes from a storage tank through a heat exchanger and to a hot water supply outlet under normal draw conditions and the water from the hot water storage tank is mixed in a predetermined proportion with cold water during high draw conditions to extend the Water supply in the hot water storage tank and cause the heat exchanger to operate at its full capacity.

In hot water supply systems for large domestic dwellings such as hotels and the like it is commonly the practice to have a large hot water storage tank which is connected to a heat exchanger through a circulating pump. The water in the tank is nearly at the desired temperature and any slight deficiencies in temperature are supplied as the water circulates through the heat exchanger on its way to the hot water supply outlet. As water is drawn from the hot water storage tank it is replaced by cold water or by hot water from the heat exchanger outlet. Thus, the water in the system is in general nearly at the desired temperature unless a large amount of hot water is drawn, in which case the cold water refilling the storage tank reduces the temperature of the water therein.

During periods in which an excessive amount of hot water is drawn and the temperature of the water in the storage tank is reduced a temperature sensor at the output of the heat exchanger activates a control which increases the flow of steam to the heat exchanger thereby causing the heat exchanger to operate at a greater capacity. In general the heat exchanger does not operate at full capacity until the amount of hot water drawn reaches approximately one-half of the capacity of the storage tank.

It can be seen that the system described above requires an extremely large storage tank since, during periods of excessive drawing of hot water, after approximately onehalf of the water has been drawn from the storage tank the water supplied to the heat exchanger will continue to decrease in temperature while the heat exchanger is already operating at maximum capacity. Therefore, as more water is drawn the heat exchanger will not be able to supply a sufiicient amount of heat and the temperature of the water at the hot water outlet will be below the desired temperature. To insure a suflicient supply of hot water from these prior art systems it is necessary to either have a storage tank approximately twice as large as the maximum of hot water to be used or to in some manner increase the maximum capacity of the heat exchanger.

In the present invention .a three-way valve is placed between the storage tank and the heat exchanger. The three-way valve has water from the storage tank flowing into one inlet and cold water from a cold water source flowing into the other inlet. The operation of the three way valve is such that the cold water inlet can be shut off so that water flows to the heat exchanger only from the storage tank or the cold water inlet can be opened so that the water from the storage tank will be mixed with cold water. The three-way valve is operated in response to a temperature sensor which is placed in the water line between the three-way valve and the heat exchanger and, optionally, a flow switch placed in the cold water supply conduit. As the temperature at the sensor increases the valve gradually opens allowing cold water to flow therethrough and mix with the water from the storage tank.

In the operation of the present device during periods when the hot water supply is being used at a normal rate or less the three-way valve allows water to flow to the heat exchanger only from the storage tank. Since the hot water is being used at a relatively low rate the cold water refilling the storage tank does not lower the temperature therein sufliciently to warrant increasing the capacity of the heat exchanger and therefore the flow switch remains open. Therefore, the heat exchanger continues to operate at a low capacity. During periods when a large quantity of hot water is being used from the supply system the flow switch is activated. The water flowing from the storage tank is initially at approximately the desired temperature of the water at the hot waer oulet. The

temperature sensor is set to operate the three-way valve at some predetermined water temperature, which is near the minimum water temperature the heat exchanger can raise to the desired water temperature. Thus, the water initially flowing from the tank activates the three-way valve and cold water is mixed therewith to lower the temperature of the mixture to the predetermined temperature. As large quantities of water are used from the storage tank and replaced by cold water the temperature of the water in the tank is lowered. The lower temperature of the water flowing from the tank lowers the temperature of the mixture of water, which is sensed by the temperature sensor and the three-way valve allows less water to mix therewith. The temperature of the water flowing into the heat exchanger is thus maintained at some value below the desired temperature at the hot water outlet. Since this water is at a much lower temperature the heat exchanger immediately begins to operate at a higher capacity to heat the water to the desired temperature.

Since the heat exchanger is operating at or near maximum capacity very soon after the start of the period during which a relatively large supply of hot water is being used and since the water being supplied to the heat exchanger is only partially supplied by the storage tank the present device can supply a very much larger quantity or" hot water with the same size tank and heat exchanger as the previous systems. Thus, the present device is a great improvement over the prior art since it is more efficient and a smaller storage tank and/ or a smaller heat exchanger can be utilized to supply the same quantity of hot water.

It is an object of the present invention to provide an improved domestic hot water storage supply system.

It is a further object of the present invention to provide a domestic hot water storage supply system which is more eflicient and utilizes a smaller storage tank and/or a smaller heat exchanger.

These and other objects of this invention will become apparent to those skilled in the art upon consideration of the accompanying specification, claims, and drawings.

Referring to the drawings, wherein like characters indicate like parts throughout the figures:

FIG. 1 is an elevational view of one embodiment of the present invention, portions thereof shown in section, illustrating the normal flow pattern;

FIG. 2 is a view similar to FIG. 1 but illustrating a high draw flow pattern;

FIG. 3 is a greatly enlarged axial sectional view of the three-way valve, portions thereof shown in elevation and portions thereof broken away;

FIG. 4 is an enlarged axial sectional view of the threeway valve, portions thereof shown in elevation showing a different mode of operation than FIG. 3; and

FIG. 5 is an elevational view of a modified form of the present invention.

In FIG. 1 an insulated storage tank has an outlet 11 for heated water and an inlet 12 for cold water. A pipe and valve 13 in the bottom of the tank are for draining of the tank during cleaning, etc. A vertical pipe 14 extending from the outlet 11 of tank 16 is connected to a T-coupling 15 one opening of which has a relief valve 16 therein. The other opening of the T-coupling 15 has a pipe 17 therein which is connected to one inlet 18 of a three-Way valve generally designated 20. Valve 23 can be seen more clearly by referring to FIGS. 3 and 4.

Referring to FIGS. 3 and 4 the numeral 21 indicates the body of the three-way valve, the numeral 22 indicates a housing which contains the actuating mechanism and the numeral 23 indicates a coupler which threads into an opening 24 in the top of the body 21 and into an opening 25 in the bottom of housing 22. Body 21 has the first inlet 18, which in the present embodiment is connected to the outlet of the storage tank 10 by means of conduits 14 and 17. Body 21 has a second inlet 26 having a conduit 27 therein which is connected to a T-coupling 28. T-coupling 28 has a conduit 29 connected thereto which is attached to a cold water supply, not shown, through a flow switch 19, which will be explained in more detail later. Body 21 of three-way valve 20 has an outlet 30 with a conduit 31 threaded therein.

As can be seen from FIGS. 3 and 4, body 21 is construced so that inlet 18 and outlet 30 are coaxial While inlet 26 is perpendicular thereto and enters from the bottom. A partition 32 having a somewhat S-shaped cross section extends across the cavity in the body 21 from a point between the inlets 18 and 26 to a point between the opening 24 and the outlet 30. The partition 32 has a hole 33 therein which is approximately horizontal and coaxial with inlet 26. Water entering inlet 18 must flow through hole 33 in the partition 32 to reach the outlet 36, while water flowing in the inlet 26 flows directly to the outlet 30.

A vertical valve stem 35 is mounted for vertical movement in the coupler 23 by means of a plurality of Tefloncoated packing rings 36. Stem 35 is mounted coaxial with inlet 26 and extends through the openings 33 in the partition 32 and slightly into an insert 37 having an inwardly projecting shoulder 38 thereon. Insert 37 is threaded into the body 21 and forms the inlet 26. A double-faced valve element 40 is fixedly attached to the lower end of the stem 35 by means of a nut 41 threaded onto the lower end of stem 35. Valve element 4%) has a composition disc 42 firmly imbedded in the lower face thereof and a composition disc 43 imbedded in the up-- treme upward position, thereby, closing the hole 33 and preventing any water from flowing into the inlet 18. It should be noted that the amounts of water flowing into the inlet 18 and the inlet 26 will be determined by the position of the valve element 40 and can be varied by moving the valve element between the upper and lower extremes.

The housing 22 has a hollow cylindrical shape with the upper portion thereof having a substantially increased radius. The lower end of the cylindrical housing 22 is closed except for the hole 25 which has the coupler 23 threaded therein. The upper end of the cylindrical housing 22 is open and has a matching cap 45 fitted thereover and flxedlyattached by means of bolts 46. Cap 45 is closed except for an axial opening 47 therein which has threaded into it a conduit 48. Conduit 48, as will be explained in more detail later, is attached to some source of pressure such as pneumatic pressure.

A piston 49 is coaxially mounted for limited axial movement in cylindrical housing 22. The upper end of piston 49 has a radially, outwardly extended flange 50 over which is secured a cup shaped housing 44 which provides a relatively large flat surface over which a diaphragm 51 is stretched. Diaphragm 51 is circular in shape and is fixedly held in place by placing the edges thereof between the upper surface of the cylindrical housing 22 and the lower surface of the cap 45 before bolting them together. The outer edge of the diaphragm 51 is slightly thicker than the remainder of the diaphragm and consequently serves as a gasket to make the junction between the cap 45 and the housing 22 airtight.

A rod 52 is fixedly attached at the upper end to the underside of piston 49 by a screw 53. Rod 53 is coaxial with piston 49 and stem 35 and the lower end of rod 52 is threaded onto the upper end of stem 35. Thus, stem 35 is fixedly attached to piston 49 and moves axially therewith.

Rod 52 is slidably mounted within a cylinder 54 which is in turn fixedly mounted coaxial with the cylindrical body 22 by means of a collar 55 on the inner periphery of the housing 22. The inner diameter of the cylinder 54 is slightly larger than the outer diameter of therod 52 so that the rod 52 is maintained coaxial with the housing 22. The outer periphery of the cylinder 54 is threaded and has engaged thereon a nut 56 which has an outside diameter slightly smaller than the inside diameter of the housing 22. Mounted between the upper surface of nut 56 and the lower surface of piston 49 is a compression spring 57 which biases the piston 49 upwardly. The amount of bias which the compression spring 57 applies to the piston 49 is dictated by the axial position of the nut 56 on the periphery of the cylinder 54. In the present embodiment the nut 56 is generally near its lower extreme on the periphery of the cylinder 54 so that the spring 57 biases the piston 49 to a position in which the valve element 40 is approximately midway between the hole 33 in partition 32 and the shoulder 38 on insert 37. Thus, in its normally biased position the valve 20 allows approximately one-half of the water flowing in the outlet 30 to flow from the inlet 18 and the other one-half of the water flowing in the outlet 30 to flow from the inlet 26.

In the operation of the valve 20 as pressure is applied through conduit 48 to the upper surface of the'diaphragrn 51 the piston 49 is forced downwardly against the bias of the compression spring 57. As the piston 49 moves downwardly the hole 33 in the partition 32 is obstructed less by the disc 43 in the valve element 40 and the inlet 26 is obstructed more by the disc 42 in the valve element 49. Thus, by varying the pressure in the conduit 48 the mixture of water from inlet 18 and from inlet 26 in outlet 39 can be varied. In general, the greater the pressure in conduit 48 the greater the amount of water flow from inlet 18 to inlet 39. e

It should be noted that while the present embodiment discloses apparatus for varying the mixture of hot water from the storage tank with cold water, which is operated by a pressure source such as fluid, the present invention is not limited to this form. In fact the present invention will operate with any apparatus that varies the proportions of hot water and cold water flowing therein. For example the apparatus disclosed can be operated by pneumatic pressure, water pressure, or steam pressure (with slight modifications) or the pressure apparatus can be changed and the valve stem 3-5 can be moved by electrical means.

The conduit 31 threaded into the outlet 30 of three-way valve 20 is threaded into one opening of a T-coupling 69 at the other end. One of the other openings in T-coupling 60 has a plug containing a temperature bulb 61 threaded therein. The temperature bulb 61 is connected to a pneumatic fiow regulator 62 by any convenient means such as electricity, etc. illustrated by the line 63. A conduit 64 connects the pneumatic flow regulator 62 to a source of pneumatic pressure and the conduit 48 attached to the three-way valve 20 is connected to the output of the pneumatic flow regulator 62. The pneumatic flow regulator 62 and the temperature bulb 61 operate in the following manner. If the temperature of the water in the T- coupling 60 is above a predetermined value this temperature is sensed by the temperature bulb 61 which sends a signal by way of line 63 to the pneumatic flow regulator 62. The signal at the pneumatic flow regulator 62 reduces the pneumatic pressure in the conduit 48 thereby allowing the three-way valve 26 to open the inlet valve 26 a predetermined amount allowing cold water from conduit 29 to flow therethrough.

The third opening in the Tcoupling 66 has one end of a conduit 65 threaded therein. The other end of the coupling 65 is threaded into the inlet of a circulating pump 66. The outlet of the circulating pump 66 has one end of a conduit 67 threaded therein the other end of which is threaded into an inlet 68 of a heat exchanger generally designated by numeral 70.

The heat exchanger 70 has two main body portions, a bell shaped portion 71 and an elongated cylindrical portion 72. The bell shaped portion 71 and the cylindrical portion 72 each have a closed end and an open end. The open ends of portions 71 and 72 are joined together to form a completely enclosed container. The bell shaped portion 71 is divided approximately into two halves by a partition 73 therein. The inlet 68 connects conduit 67 with one-half of the bell shaped portion 71. An outlet 74 connects the other half of the bell shaped portion 71 with a conduit 75. A partition 76 fixedly connected at the junction of the bell shaped portion 71 and the cylindrical portion 72 provides a water and steam tight partition between the two portions 71 and 72.

A plurality of rigid elongated conduits 77 and 78 are embedded fixedly horizontal in the partition 76 and extend from the partition 76 approximately the length of the cylindrical portion 72. All of the conduits 77 and 78 are joined together at their other end by a small tank-like structure 79. The end of the conduits 77 embedded in partition 76 open into the inlet half of the bell shaped portion 71 While the other ends open into the tank-like structure 79. The ends of the conduits 78 embedded in the partition 76 open into the outlet half of the bell shaped portion 71 while the other ends open into the tank-like structure 79. Thus, water entering the inlet 68 from conduit 67 is free to circulate through conduit 77, tank 79, conduit 78 to the outlet 74.

The cylindrical portion 72 of heat exchanger 70 has a steam inlet 80 therein with one end of a steam conduit 81 fixedly attached thereto. The other end of steam conduit 81 is threaded into a steam flow regulator 82 which controls the amount of steam supplied to conduit 81. Steam flow regulator 82 is connected to a source of steam, not

shown, by means of a conduit 83. The steam flow regulator 82 is operated by some convenient means such as the mechanism 84, which may be for example electrical. The cylindrical portion 72 of heat exchanger 70 also has an outlet 85 having one end of a conduit 86 fixedly attached therein. The other end of the conduit 86 is attached to a condensate strainer 87. The condensate strainer has one end of a conduit 88 attached thereto the other end of which is attached to a steam trap 89. The cylindrical portion 72 of heat exchanger 70 also has a vent 90 attached thereto to eliminate the air in tank 14) to prevent air binding and the like.

It should be noted that while the present embodiment utilizes a steam energized heat exchanger 79 any method of heating the exchanger 70 would be within the scope of this invention. The present invention would operate with any of a variety of heat exchangers in place of heat exchanger 70 some examples of which are hot air, electrical, etc.

A temperature sensing element 91 is mounted in the bell shaped portion 71 of the heat exchanger 70 near the outlet 74. The temperature sensing element 91 is connected to the steam valve operating mechanism 84 by some means, such as electrical, denoted by the line 92. The steam fiow regulator operating mechanism 34 operates in a fashion such that when the temperature sensing element 91 senses a reduction in temperature of the water passing out of the outlet 74 the mechanism 84 increases the flow of steam through the steam flow regulator 82 thereby increasing the capacity of the heat exchanger 70.

In FIGS. 1 and 2 a substantial amount of the elongated cylindrical portion 72 of the heat exchanger 76 is mounted within the storage tank 10. Thus, the heat exchanger 70 serves a dual function. While the heat exchanger 70 is heating water passing from the inlet 63 through the conduits 77 and 73 to the outlet 74, heat lost through the side of the cylindrical portion 72 will be absorbed by the water in the storage tank 10. However, this is simply one possible embodiment of the present invention and by referring to FIG. 5 a second embodiment can be seen in which the storage tank 19' and the heat exchanger 7 0' are separate and independent. It should be noted that everything else in FIG. 5 is connected and operates similar to the structure in FIGS. 1 and 2. The apparatus in FIG. 5 similar to the apparatus in FIG. 1 has been given similar numbers with a prime added to denote an alternate embodiment.

The open end of the conduit 75 is threaded into a T- coupling 93. One of the openings in the T-coupling 93 has a conduit 94 threaded therein. The conduit 94 is a hot water supply outlet. The other opening in the T-coupling 93 has one end of a coupling 95 threaded therein the other end of which is threaded into a check valve 96. Check valve 96 is connected to a T-coupling 97 by means of a short conduit 98. One of the openings in the T-coupling 97 is connected to the inlet 12 of the storage tank 10 by means of a conduit 99. The other opening in the T-coupling 97 is connected to the T -coupling 28 by means of a conduit 100. Conduit 100 carries cold water from the conduit 29 to the inlet 12 of storage tank 10. Check valve 96 prevents cold water from flowing through conduit 95 to conduit 94.

Flow switch 19 in the cold water supply conduit 29 is any water flow sensor which can be set to operate when the flow reaches a predetermined value and it can operate by any of the well-known methods except that it should be compatible with the temperature sensor 61 and the flow regulator 62. The flow switch 19 is connected to the flow regulator 62 by any means also compatible with the operation and such connection is indicated by the line 34. The operation of the flow switch 19 is such that when the hot water being used at outlet 94 is normal or below the flow switch 19 is open and the flow regulator 62 applies maximum pressure to the three-way valve 20, closing oh? the inlet 26. When the flow of water through the flow switch 19 reaches a predetermined value the flow switch 19 closes and the pressure allowed in line 48 by the flow regulator 62 is determined by the temperature sensor 61. It should be noted that the flow switch 19 is optional and the present system will operate without it but the circuit containing the three-way valve 26 and the sensor 61 has a tendency to oscillate slightly during periods when small amounts of hot water are being used.

In the operation of the present device refer first to FIG. 1. The water in the storage tank 10 is maintained near the desired heat by the action of the heat exchanger 70 therein. When normal quantities of hot water are drawn from the conduit 94 the three-Way valve is in the position shown in FIG. 3. That is, Water is flowing from conduit 17 to conduit 31 and conduit 27 is closed. Since the circulating pump 66 is operating continuously, water is drawn from the storage tank 10 through conduits 14 and 17 to the three-way valve 20 where it passes to conduit 31 and then past the temperature sensing element 61 to conduit 65 and into the circulating pump 66. Water 3 is forced out of the circulating pump 66 through conduit 67 and into the heat exchanger 70 where it passes through the conduits 77 and 78, over the temperature sensing element 71 and out into conduit 75. Since the water entering the heat exchanger 70 is nearly at the desired temperature, sensing element 91 causes steam flow valve 82 to pass only a small amount of steam to heat the water in the conduits 77 and 78. Thus, the heat exchanger 70 is operating at a very low capacity. As water is drawn from the storage tank 10 cold water enters conduit 29 from the source and passes through conduit 100 and conduit 99 to the inlet 12 in storage tank 10 where it mixes with the hot water already there to cool that water slightly.

Referring to FIG. 2 assume that a large quantity of water is being drawn from the conduit 94 and, therefore, flow switch 19 has operated. Initially only hot water from tank 10 passes through the valve 20. This hot water is sensed by the temperature sensor 61 which applies a signal to the pneumatic flow regulator 62. The flow regulator 62 decreases the pressure applied to the valve 20 whereby inlet 26 is opened allowing cold water to flow therein and mix with the hot water from tank 10. The flow regulator 62 decreases the pneumatic pressure on valve 20 until the temperature of the water at sensor 61 has dropped to a predetermined value. This predetermined value will be in more heat is escaping to the water in the storage tank 10 and, therefore, the cold water entering the inlet 12 does not reduce the temperature of the entire supply of water in the storage tank 10 as far as it would if the heat exchanger 70 were operating at some lesser capacity. When the amount of hot water being drawn from the conduit 94 returns to a normal value or less, the flow switch 19 opens and hot water is circulated through conduit 95, 'check valve 96 and conduit 99 to inlet 12 of tank 10 so that the temperature of the water within the storage tank 10 quickly rises to nearly the desired value.

Thus, the present device can provide the required amount of hot Water during large draw periods. or normal draw periods and utilizes a much smaller storage tank 10 and/ or a smaller heat exchanger 70. Also, the present device is much more efficient because'hot water is always available whereas in the prior art systems the storage tank could be depleted of hot water and the heat exchanger is not capable of heating cold water to the desired value, so that in the prior art systems once they are depleted of hot water, that is the temperature of the water 3 in the storage tank is reduced to a predetermined value, no more hot water is available for a long period of time.

While I have shown and described a specific embodi ment of this invention, further modifications and improvements will occur to those skilled in the art. I desire it to be understood, therefore, that this invention is not limited to the particular form shown and I intend in the appended general approximately the minimum water temperature the heat exchanger 70 can raise to the water temperature desired at the hot water outlet 94.

As water is drawn from outlet 11 in the storage tank 10 it is replaced by cold water at inlet 12. Cold water entering the storage tank 10 gradually reduces the overall temperature of the water therein. The valve 20 operates in a somewhat linear fashion so that as the temperature of the water in the tank 10 cools and the temperature of the blended water leaving the valve 20 cools, sensor 61 causes flow regulator 62 to increase the pneumatic pressure which in turn causes the valve 20 to allow less cold water to flow through inlet 26. Thus, the temperature of the water at sensor 61 remains at approximately the predetermined 'much lower temperature after the valve 20 operates, the

temperature sensing element 91 at the outlet 74 transmits a signal to the mechanism 84 and the steam flow regulator 82 opens to allow more steam to enter the heat exchanger 70. Thus, the heat exchanger 70 is operating at or near maximumcapacity even though the water in the storage tank 10 is still relatively near the desired value. Since the hot water from the storage tank 10 is being'blended with cold water from the conduit 29 in the three-way valve 2!) the hot water will not be depleted as quickly as it would be if only hot water were being used. Also, since the heat exchanger 70 is operating at or near maximum capacity claims to cover all modifications which do not depart from the spirit and scope of this invention.

I claim:

1. A domestic hot water storage supply system comprising:

(a) a hot water storage tank having a water outlet and inlet;

(b) cold water supply conduit adapted to be attached to a source of cold water;

(c) a three-way water valve having a first inlet nected to said storage tank outlet, a second inlet connected to said cold water supply conduit, and an outlet, said valve allowing quantities of water from both of said valve inlets to pass to said valve outlet and 3 operating to decrease the flow of water from said second valve inlet;

(d) a circulating pump having an inlet and an outlet;

(e) a heat exchanger having'a water inlet and outlet and a first temperature sensor at said outlet;

(f) energizing means operatively connected to said heat exchanger for supplying energy thereto up to a maximum amount which defines the maximum capacity of said heat exchanger and said heat exchanger being controlled by said first temperature sensor at said outlet for varying the enregy supplied to said heat exchanger to maintain the temperature of the water at the outlet substantially constant;

(-g) conduit means including a second temperature sensor connecting said three-way valve outlet to said pump inlet and further conduit means connecting said pump outlet to said heat exchanger inlet;

(h) control means operatively connected to said second temperature sensor and to said three-way valve for operating said three-way valve to adjust the flow of cold water through said second valve inlet and hot 'water through said first valve inlet to provide water to the inlet of saidheat exchanger having a temperature such that said heat exchanger operates at approximately its maximum capacity during periods of relatively high water usage and to substantially close said second valve inlet during periods of relatively low water usage} (i) conduit means connecting said heat exchanger outlet to a hot water supply outlet and further connecting said heat exchanger outlet to said storage tank inlet through a check'valve, for allowing water to COD- flow from said heat exchanger outlet to said storage tank inlet; and

(1) additional conduit; means connecting said cold water supply conduit to said storage tank inlet for supplying cold Water to replenish said storage tank.

2. The domestic hot Water storage supply system of claim 1 wherein at least a portion of the steam operated heat exchanger is positioned within the storage tank for supplying heat to water Within said tank as well as water within said heat exchanger.

3. The domestic hot water storage supply system of claim 1 wherein the control means includes flow switch means mounted in said cold water supply means and operatively connected to said control means for causing said References Cited UNITED STATES PATENTS 2,236,087 3/1941 Detwiler 236-18 2,756,739 7/1956 Schaub 126-362 3,053,516 9/1962 Killebrew 16539 FREDERICK L. MATTESON, JR., Primary Examiner. ROBERT A. DUA, Examiner. 

1. A DOMESTIC HOT WATER STORAGE SUPPLY SYSTEM COMPRISING: (A) A HOT WATER STORAGE TANK HAVING A WATER OUTLET AND INLET; (B) COLD WATER SUPPLY CONDUIT ADAPTED TO BE ATTACHED TO A SOURCE OF COLD WATER; (C) A THREE-WAY WATER VALVE HAVING A FIRST INLET CONNECTED TO SAID STORAGE TANK OUTLWT, A SECOND INLET CONNECTED TO SAID COLD WATER SUPPLY CONDUIT, AND AN OUTLET, SAID VALVE ALLOWING QUANTITIES OF WATER FROM BOTH OF SAID VALVE INLETS TO PASS TO SAID VALVE OUTLET AND OPERATING TO DECREASE THE FLOW OF WATER FROM SAID SECOND VALVE INLET; (D) A CIRCULATING PUMP HAVING AN INLET AND AN OUTLET; (E) A HEAT EXCHANGER HAVING A WATER INLET AND OUTLET AND A FIRST TEMPERATURE SENSOR AT SAID OUTLET; (F) ENERGIZING MEANS OPERATIVELY CONNECTED TO SAID HEAT EXCHANGER FOR SUPPLYING ENERGY THERETO UP TO A MAXIMUM AMOUNT WHICH DEFINES THE MAXIMUM CAPACITY OF SAID HEAT EXCHANGER AND SAID HEAT EXCHANGER BEING CONTROLLED BY SAID FIRST TEMPERATURE SENSOR AT SAID OUTLET FOR VARYING THE ENERGY SUPPLIED TO SAID HEAT EXCHANGER TO MAINTAIN THE TEMPERATURE OF THE WATER AT THE OUTLET SUBSTANTIALLY CONSTANT: (G) CONDUIT MEANS INCLUDING A SECOND TEMPERATURE SENSOR CONNECTING SAID THEREE-WAY VALVE OUTLET TO SAID PUMP INLET AND FURTHER CONDUIT MEANS CONNECTING SAID PUMP OUTLET TO SAID HEAT EXCHANGER INLET; (H) CONTROL MEANS OPERATIVELY CONNECTED TO SAID SECOND TEMPERATURE SENSOR AND TO SAID THREE-WAY VALVE FOR OPERATING SAID THREE-WAY VALVE TO ADJUST THE FLOW OF COLD WATER THROUGH SAID SECOND VALVE INLET AND HOT WATER THROUGH SAID FIRST VALVE INLET TO PROVIDE WATER TO THE INLET OF SAID HEAT EXCHANGER HAVING A TEMPERATURE SUCH THAT SAID HEAT EXCHANGER OPERATES AT APPROXIMATELY ITS MAXIMUM CAPACITY DURING PERIODS OF RELATIVELY HIGH WATER USAGE AND TO SUBSTANTIALLY CLOSE SAID SECOND VALVE INLET DURING PERIODS OF RELATIVELY LOW WATER USAGE; (I) CONDUIT MEANS CONNECTING SAID HEAT EXCHANGER OUTLET TO A HOT WATER SUPPLY OUTLET AND FURTHER CONNECTING SAID HEAT EXCHANGER OUTLET TO SAID STORAGE TANK INLET THROUGH A CHECK VALVE, FOR ALLOWING WATER TO FLOW FROM SAID HEAT EXCHANGER OUTLET TO SAID STORAGE TANK INLET; AND (J) ADDITIONAL CONDUIT MEANS CONNECTING SAID COLD WATER SUPPLY CONDUIT TO SAID STORAGE TANK INLET FOR SUPPLYING COLD WATER TO REPLENISH SAID STORAGE TANK. 